US2904416A - Petroleum distillate fuels - Google Patents

Description

United States Patent PETROLEUM DISTILLATE FUELS John V. Clarke, Jr., Cranford, and Stephen J. Metro,

Scotch Plains, N.J., and John O. Smith, Jr., Swampscott, Mass, assignors to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Application October 30, 1957 Serial No. 693,246

7 Claims. (21. 44-72 The present invention relates to improved hydrocarbon oil compositions and more particularly relates to improved petroleum distillate fuels boiling in the range be tween about 75 F. and about 750 F. having incorporated therein a new class of additive materials which markedly improve the stability of such fuels, reduce rusting and corrosion of metallic surfaces with which the fuels come into contact in the presence of water, and greatly alleviate the explosive hazards involved in handling such fuels.

Instability due to the presence of unsaturated hydrocarbons and other relatively reactive materials in petroleum distillate fuels boiling between about 75 F. and about 750 F. constitutes a serious problem in connection the use and handling of such fuels. The unstable constituents of the fuels gradually oxidize or otherwise react during storage to form insoluble sludge and sediment which are often responsible for the subsequent clogging .of fuel lines, filters and orifices in engines and ,burner systems in which the fuels are used. Such clogging usually necessitates the shutting down and cleaning of the fuel and corrosion of metals in the presence of moisture is considered a serious deficiency in petroleum distillate fuels. Such fuels are normally stored in tanks equipped with breather devices to take care of expansion and contraction dueto temperature fluctuations. Moisture from the air which enters the tank condenses on the tank walls and results in theformation of a highly corrosive aqueous phase which. quickly nus-ts out tank bottoms. Small amounts of waterentrained in fuel from such-tanks may cause the rusting and corrosion offuel lines, engines, nozclass of additive materials which, when incorporated in r petroleum distillate fuels, overcome the difficulties enumerated above. It has been found that the additive materials'of the invention effectively stabilize petroleum distillate fuels and prevent the oxidation of unstable fuel constituents; reduce the rusting and corrosion of wet or 2,904,416 Patented Sept. 15, 1959 damp metallic surfaces with which the fuels come into contact; and increase the electrical conductivity of the fuels, thus permitting static electricity to dissipate rapidly and reducing the explosive hazards involved in handling such fuels. Heretofore it has been necessary to incorporate separate additives in such fuels in order to overcome these deficiencies. The additives of this invention not only obviate the necessity for the use of multiple additives but in addition are considerably more effective than many of the additive material heretofore used.

The additive materials which are incorporated into the fuels of the present invention are tetra alkyl ammonium salts of alkyl polyalkyleneoxy esters of phosphoric acid and have the general formula where R is an alkyl group containing from 2 to 13 carbon atoms, R is a divalent aliphatic hydrocarbon radical having from 2 to 8 carbon atoms, n is from 8 to 18, x is 1 or 2, and R" is an-alkyl group containing from 1 to 4 carbon atoms. Specific examples of such compounds include the tetra methyl ammonium salt of ethyl pentapr'opoxy phosphate, the tetra ethyl ammonium salt of propyl octaethoxy phosphate, the tetra ethyl ammonium 'salt of butyl dodecapropoxy phosphate, the tetra prop yl ammonium salt of pentyl decapropoxy phosphate, and the tetra butyl ammonium salt of dodecyl hexadecabutoxy phosphoric acid. The tetra ethyl ammonium salts of the alkyl polypropoxy phosphates are preferred for purposes of the present invention and the tetra ethyl ammonium salt of n-butyl dodecapropoxy phosphate is particularly preferred.

The alkyl polyalkyleneoxy esters of phosphoric acid from which the ionic additives of the present invention are prepared are the reaction products of monoethers of polyalkylene glycols -'with P 0 These monoethers are well known articles of commerce and are prepared by condensing an alkylene oxide such as ethylene oxide, propylene oxide or mixtures of the two, with an aliphatic compound containing a hydroxyl group, an alcohol for example. Specific examples of these materials include n-tridecyl hexaethylene glycol monoether, isotridecyl nonapropylene glycol monoether, n-decyl pcntadecabutoxy alcohol and n-butyl dodecaisopropoxy alcohol. Also included are monoethers of polyglycols wherein the polymeric chain may consist of different alkylene oxide groups, for example ethylene oxide and propylene oxide in the same chain.

These products made by the condensation of alkylene oxides are mixtures of monoethers of polyglycols of varying chain length. The assignment of a formula such as in preparing the additives of the present invention is immaterial so long as the chain lengths lie Within the limits outlined above. Monoethers suitable for use in preparing the phosphates from which the additives are made are fully described in US. Patents 2,425,755 and 2,425,845.

In preparing the phosphates, equimolar quantifies of the monoether and the phosphorus pentoxide are mixed and heated at a temperature of from about 80 F. to 450 F. for a period of from 0.1 to hours. Nitrogen or other inert gas may be bubbled through the reaction mixture in order to provide agitation, to prevent oxidation of the reactant material, and to assist in carrying away any water which may be formed. Upon completion of the reaction, the mixture is filtered and the phosphate ester may be separated from the unreacted material by vacuum distillation or other procedures well known in the art. Normally about 50% conversion to the mono phosphate is obtained.

The tetra alkyl ammonium salts of the phosphates formed as described above are prepared by treating the phosphate with a tetra alkyl ammonium hydroxide, e.g. tetra ethyl ammonium hydroxide. The hydroxide is preferably employed in aqueous solution and may he added to the phosphate in the presence of a suitable solvent such as benzene. The reactants are preferably mixed in equimolar amounts. The reaction mixture is then refluxed at a temperature of from about 140 F. to about 212 F. for a period of from about 2 to about 6 hours. Water formed by the reaction and the water initially present are removed during the reaction and the resulting product is substantially anhydrous, although I a slight haze may be present. The product may be filtered to remove this haze and the solvent employed may then be removed by vacuum distillation to obtain the final product.

The petroleum distillate fuels in which the additive materials of the invention are employed consist of a major proportion, at least 95%, of liquid hydrocarbons boiling at temperatures between about 70 F. and about 750 F. These fuels include gasolines such as aviation,

marine and automotive or motor gasolines, aviation turbo-jet fuels such as JP-l, JP-4 and JP-S fuels, and diesel fuels such as marine, stationary and automotive diesel engine fuels.

Gasoline consists of at least 95 percent of a mixture of volatile hydrocarbons and may contain various beneficial additives such as antiknock agents, scavenging agents, antioxidants, dyes, anti-icing agents and solvent oils in a total additive concentration not exceeding 5 percent by weight.

The volatility of gasoline is such that it has vapor pressures between 5 and 15 pounds per square inch at a temperature of 100 F. when determined in accordance with ASTM Method D 323-56. It has a boiling range between 75 F. and 450 F. when determined by ASTM Method D 86-56. Aviation gastion D 439-56 T as falling within three grades and have end points not exceeding 450 F. The viscosity of gasolines is between 0.264 and 1.0 centistokes at 100 F.

Aviation turbo-jet fuel consists of at least 95 percent oi a mixture of volatile hydrocarbons. It is defined by Military pecifications MIL-F-5616 and MIL-F- 5624 C. Its volatility is such that its end point does-not exceed 572 F. Its viscosity is between 0.5 and 1.5 centistokes at 100 F.

Diesel fuels as referred to in connection with the inp vention consist of at least 95% of a mixture of hydrocarbons boiling between 250 F. and 750 F. either by ASTM Method D 86-56 when their end points do not exceed 600 F. or by ASTM Method D 158-54. Diesel fuels are defined by ASTM Specification D 975-53 T and fall into Grades 1D, 2D and 4D, in allof which the additive materials of the invention may be used. They have viscosities between 1.4 and 26.4 centistokes.

The liquid fuels in which the additive materials may be '4 incorporated thus comprise at least by weight of a mixture of hydrocarbons having a boiling range between the limits of 75 F. and 750 F. and a viscosity between the limits of 0.264 and 26.4 centistokes at F.

The additives may be incorporated in such fuels in concentrations of from about 0.001% by weight to about 0.5% by weight. Concentrations in the range between about 0.005% to about 0.1% by weight are particularly effective.

In order to further illustrate the invention, reference is made to the following examples.

EXAMPLE I N-butyl dodecapropoxy mono-phosphate was prepared by mixing 96 wt. per cent of monobutyl dodecapropoxy glycol obtained commercially with 4% by wt. of phosphorous pentoxide. The mixture was heated to a temperature of 300 F. and held at that temperature for a period of 4 hours. Nitrogen was constantly bubbled through the mixture to provide agitation, prevent oxidation and carry away moisture formed. At the end of the 4 hour period, the reaction mixture was cooled, filtered, and the phosphate formed was recovered. Analysis showed that about 50% of the starting material was converted to the mono-phosphate and a small amount of the diphosphate and that the product contained 1.7 percent of phosphorus and had 'a, molecular weight of 889.

The tetra ethyl ammonium salt of the n-butyl dodecapropoxy phosphate thus formed was prepared by mixing 100 grams of the n-butyl dodecapropoxy phosphate with 83' grams of a 10% aqueous solution of tetar ethyl ammonium hydroxide in cc. of benzene. The mixture was refluxed at a temperature of 176 F. for a period of 4 hours in a side arm type refluxing apparatus. The product obtained was filtered through a paper filter and'benzene was subsequently removed by vacuum distillation. Analysis confirmed the formation of the tetra ethyl ammonium salt of the n-butyl dodecapropoxy phosphate.

EXAMPLE H The additive material produced as described above was incorporated into examples of a premium quality commercial gasoline and these samples were subjected to an ASTM Breakdown Test in order to test the effectiveness of the additive for reducing oxidation of the gasoline.

Typical inspections of the gasoline used are as follows:

' The additive was incorporated in the gasoline in a concentration of 0.03% by weight. Measured amounts of the gasoline containing the additive and the same gasolinewithout the additive were placed in glass containers in a bomb. The bomb was filled with pure oxygen at a pressurewof 100 psi. and placed in a boiling water bath. The bomb pressure gauge was read periodically .andthe test was continued until oxidation of the fuel causedzthe pressure to drop at a rate of 2 p.s.i. per 15 minute-interval. The time required to-reach this rate is A.S.T.M. breakdown test A.S.T.M, breakdown time, minutes Fuel:

Base gasoline s 260 Base gasoline+0.03 wt. percent of tetraethyl ammonium salt of n-butyl dodecaproxy phosphate 370 From the above it can be seen that the time required for oxidation of the fuel was significantly increased by the addition of the additive material. The test employed is a severe one and it will be appreciated that the improvement in stability was of considerable magnitude.

EXAMPLE III 6 fined by U.S. Military Specification MIL-E5624 C boiling between about 300 F. and 550 F. and samples of the same fuel to which had been added 0.01 wt. percent of the tetra ethyl ammonium salt of u-butyl dodecapropoxy monophosphate were placed in a glass system and pumped at a rate of 1500 cc. per minute through a glass wool plug. The time required for a 7.0 kilovolt dis-' charge to be' obtained from a condenser placed in the system was measured. In a second series of tests the time in seconds to charge a 125 micromicrofarad condenser to 2.5 kilovolts when a -'7 .0 kilovolt charge-was applied to the test liquid was measured. In a third series of tests 80 milliliters of each fuel were shaken with milliliters of water for 2 minutes and then allowed to settle for 5 minutes. The amount of water lost in each sample was then determined. A jet fuel containing calcium sulfonate, an ionic material, and other materials containing the active groups of the additives of the invention were also tested. The results of these tests are In order to demonstrate the rust inhibiting properties 0 shown below.

Efiect of additives on static electricity and water tolerance of jet fuels [0.01 Weight percent additive in jet fuel kerosine] Pumping test 1 Oqnduc- Water Additive tlvity tolerance 3 test 2 Init. 2 min. 10 min.

None 6 sec. 7 sec 10 sec... 70.0 sec.- O.5 m1. Tetra ethyl ammonium salt of n-butyl dodecapropoxy phosphate 2. 0 O.5.

Calcium sulfonate Reaction product of amine and n-butyl dodecapropoxy phosphate. R%acion (product of polymerized olefin and tetra ethyl ammon m y lOXl e 1 Pumping test: Time in seconds for successive 7.0 kv. discharge at indicated pumping time. Flow rate of 1,500 cc./min. thru glass wool plug.

2 Conductivity test: Time in seconds to charge 125 uni. condenser to 2.5 kv. when 7.0 kv. is applied thru test liquid. 3 Water tolerance: Loss of H20 in ml. when 80 ml. of fuel are shaken with 20 ml. of H20. Shake for 2 min., allow to settle for 5 min., read water loss on graduated cylinder scale.

4 N 0 discharge.

6 Mixture of 0 -02 tertiary alkyl primary amines.

of the additive materials, a commercial gasoline similar to that employed in the preceding tests was subjected to a rust test with and without the additive. 500 cc. samples of the gasoline and the gasoline containing the additive were each mixed with 500 cc. of tap water and polished steel test panels were immersed in each sample so that half of each panel was in the aqueous phase and half was in the upper gasoline phase. Air was bubbled through the liquid at a rate of 500 cc. per minute for one hour. The samples were then sealed and the test panels were observed periodically for evidence of rusting. It was found that the sample containing the tetra ethyl ammonium salt of n butyl dodecapropoxy phosphate as an additive material was completely protected against rusting, while severe rusting took place in the samples containing no additive. The data obtained in this test are shown below.

Advantages of tetra alkyl ammonium salts of alkylpolyalkyleneoxy phosphates in inhibiting rust Sample Appearance of panel Base gasoline Heavy rust in Shours. Base gasoline 0.03 weight percent of tetra ethyl ammonium salt of rl-butyl dodecapropoxy phosphate No rust in 75 days.

EXAMPLE IV The effectiveness of the additive materials of the invention as anti-static agents is shown by pumping tests, conductivity tests and water tolerance tests carried out upon a turbo-jet aviation fuel with and without the additive. Samples of a turbo-jet fuel of Grade JP-5 as de- The data in the above table clearly demonstrate the superiority of the additives of the invention as antistatic agents over similar materials. It should be noted that, while calcium sulfonate, also an ionic material, reduced static buildup by increasing the conductivity of the fuel, this additive was unsatisfactory for use as an anti-static agent because it increased the solubility of water in the fuel and so failed to pass the water tolerance test. Similarly, the last two items in the table show that the desired properties are not due to the tetra alkyl group or the phosphate group alone but are peculiar to the reaction product containing both groups. Only the tetra ethyl ammonium salt of n-butyl dodecapropoxy phosphate, of the materials tested, effectively reduced static build-up without increasing water solubility in the fuel unduly.

It is believed the data presented in the foregoing examples clearly demonstrate the efiectiveness of the additive materials of the invention for stabilizing petroleum distillate fuels, inhibiting such fuels again-st rust and corrosion, and reducing static build-up in such fuels. It will be understood that the additive materials of the invention may be incorporated into such fuels in conjunction with other additive materials intended to correct other fuel deficiencies.

What is claimed is:

l. A petroleum distillate fuel boiling in the range between about 75 F. and about 750 F. having incorporated therein from about 0.001% to about 0.5% by weight of a tetra alkyl ammonium salt of an alkylpolyalkyleneoxy ester of phosphoric acid having the formula where R is an alkyl group containing from 2 to 13 carbon atoms, R is a divalent aliphatic hydrocarbon radical having from 2 to 8 carbon atoms, n is from 8 to 1 8, x is an integer from 1 to 2, and R is an alkyl group containing from 1 to 4 carbon atoms.

.2. A fuel as defined by claim 1 wherein said ester is an alkyl polypropoxy ester.

3. A fuel as defined by claim 1 wherein said ester is an alkyl polyethoxy ester. y

4. A fuel as defined by claim 1 wherein said salt is a tetra ethyl ammonium salt.

5. A fuel as defined by claim 1 wherein said ester is n-butyl dodecapropoxy phosphate.

6. A petroleum distillate fuel boiling in the range between about 75 F. and about 750 F. having incorporated therein from about 0.001% to about 0.5% by weight of a tetra alkyl ammonium salt of n-butyl dodecapropoxy phosphate, the alkyl groups in the tetra alkylammonium radical of said salt each containing from 1 to 4 carbon atoms.

7. A fuel as defined by claim 6 wherein said salt is present in a. concentration of from about 0.005% to 10 about 0.1% by weight.

No references cited.

Claims (1)

1. A PETROLEUM DISTILLATE FUEL BOILING IN THE RANGE BETWEEN ABOUT 75*F. AND ABOUT 750*F. HAVING INCORPORATED THEREIN FROM ABOUT 0.001% TO ABOUT 0.5% BY WEIGHT OF A TETRA ALKYL AMMONIUM SALT OF AN ALKYLPOLYALKYLENEOXY ESTER OF PHOSPHORIC ACID HAVING THE FORMULA